全文获取类型
收费全文 | 57878篇 |
免费 | 3754篇 |
国内免费 | 116篇 |
专业分类
耳鼻咽喉 | 549篇 |
儿科学 | 2332篇 |
妇产科学 | 1569篇 |
基础医学 | 7248篇 |
口腔科学 | 595篇 |
临床医学 | 8767篇 |
内科学 | 10021篇 |
皮肤病学 | 794篇 |
神经病学 | 5473篇 |
特种医学 | 1081篇 |
外科学 | 4933篇 |
综合类 | 632篇 |
一般理论 | 110篇 |
预防医学 | 8063篇 |
眼科学 | 771篇 |
药学 | 3866篇 |
中国医学 | 62篇 |
肿瘤学 | 4882篇 |
出版年
2023年 | 304篇 |
2022年 | 446篇 |
2021年 | 1049篇 |
2020年 | 721篇 |
2019年 | 1081篇 |
2018年 | 1231篇 |
2017年 | 1014篇 |
2016年 | 1088篇 |
2015年 | 1262篇 |
2014年 | 1769篇 |
2013年 | 2807篇 |
2012年 | 4029篇 |
2011年 | 4324篇 |
2010年 | 2404篇 |
2009年 | 2176篇 |
2008年 | 3915篇 |
2007年 | 4184篇 |
2006年 | 4016篇 |
2005年 | 4168篇 |
2004年 | 3977篇 |
2003年 | 3766篇 |
2002年 | 3448篇 |
2001年 | 551篇 |
2000年 | 421篇 |
1999年 | 558篇 |
1998年 | 728篇 |
1997年 | 629篇 |
1996年 | 505篇 |
1995年 | 505篇 |
1994年 | 460篇 |
1993年 | 351篇 |
1992年 | 295篇 |
1991年 | 264篇 |
1990年 | 229篇 |
1989年 | 241篇 |
1988年 | 218篇 |
1987年 | 210篇 |
1986年 | 220篇 |
1985年 | 216篇 |
1984年 | 225篇 |
1983年 | 203篇 |
1982年 | 248篇 |
1981年 | 221篇 |
1980年 | 177篇 |
1979年 | 121篇 |
1978年 | 138篇 |
1977年 | 73篇 |
1976年 | 72篇 |
1975年 | 75篇 |
1974年 | 86篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
51.
52.
We have previously described the development of new hepatic surgical techniques using the ultrasonic surgical dissector. With 10 years' experience, we have found that major liver resections have been simplified and that the technique is repeatable in hands other than our own. Thirty-three patients had 37 tumors, averaging 5.65 cm in size, resected with an average blood loss of only 1,020 mL per case, which included 5 right trisegmentectomies, 12 lobectomies, 15 segmental resections, and 4 subsegmental resections. Twenty-two patients had metastatic colorectal cancer. Blood transfusion requirements averaged only 2.24 units in long-term survivors, which was significantly less than the 3.5 units received by patients who have since died (p = 0.092). There were no operative deaths. The median survival of these 22 patients was 56 months, and the 5-year actuarial survival rate was 35%. All of the early deaths occurred in patients with more than four tumors, and no patient with less than four tumors died before 42 months with recurrent disease. Six patients had bilateral tumors, and the fact that patients survived into the fourth and fifth post-resectional year indicates that resection was worthwhile. All these patients had Dukes' C primary tumors, but we found no statistical difference in survival between patients with Dukes' B and Dukes' C lesions. The results indicate that hepatic resection with the ultrasonic surgical dissector decreases blood loss, requires few transfusions, is safe to perform, and is associated with excellent long-term survival. 相似文献
53.
Ellen A. Eisen Paige E. Tolbert Marilyn F. Hallock Richard R. Monson Thomas J. Smith Susan R. Woskie 《American journal of industrial medicine》1994,26(2):185-202
A case-control study of larynx cancer was conducted within a cohort of automobile workers exposed to metal working fluids, commonly referred to as machining fluids (MF). Results are based on 108 cases of larynx cancer and 5:1 matched controls. Risks associated with specific types of MF, as well as specific components of the fluids were evaluated. Based on a retrospective exposure assessment, lifetime exposures to straight and soluble fluids, grinding particulate, biocides, selected metals, sulfur, and chlorine were examined. Exposure to asbestos and acid mists at two of the three study sites was also characterized. Results suggest that straight mineral oils are associated with almost a two-fold excess in larynx cancer risk. There was also evidence of an association with elemental sulfur, commonly added to straight MF to improve the integrity of the materials under extreme pressure and heat. It is not clear whether sulfur is causally related to an excess relative risk of larynx cancer or whether the observed association is the result of unmeasured confounding by another contaminant or process feature. For example, the high stress operations that require MF enriched with sulfur are also more likely to produce polycyclic aromatic hydrocarbons (PAHs) during the process. Thus, the observed association with sulfur may be due to an association with PAH. The finding of excess risk of laryngeal cancer associated with MF is consistent with several previous reports in the literature. This is the first study, however, to distinguish straight mineral oils from other types of MF. Based on these findings, a general reduction in concentrations of straight mineral oil particulate in occupational environments would be prudent. 相似文献
54.
Christiane Eckhardt Jesse S Halvosa Susan M Ray Henry M Blumberg 《Infection control and hospital epidemiology》2003,24(6):460-461
Methicillin-resistant Staphylococcus aureus (MRSA) has traditionally been a nosocomial pathogen. However, several recent studies have noted community-acquired MRSA among young, healthy patients with no risk factors or healthcare system exposure. We report the transmission of a strain of community-acquired MRSA in our neonatal intensive care unit. 相似文献
55.
T G Babb D Korzick M Meador J L Hodgson E R Buskirk 《International journal of obesity (2005)》1991,15(1):59-65
To investigate the effect of moderate obesity on ventilatory responses to graded exercise, we compared the ventilatory responses of ten moderately obese (35 +/- 5 percent body fat) and nine leaner women (22 +/- 2 percent body fat) during walking on a treadmill with incremental increases in percent grade. Speed remained constant at 3.0 mph. In the obese women, VO2 in l/min and ml/FFW/min, fb (b/min), VE (l/min), and HR were significantly greater (P less than 0.05) at all four absolute workloads. At 10.0 and 12.5 percent grade, VO2 (ml/kg/min) was smaller and VE/VO2 was greater in the obese women. The difference in VE/VO2 suggests a lower ventilatory threshold for the obese women. Percent VO2 max and R (VCO2/VO2) were significantly different at 12.5 percent grade only. When VO2 was divided by HR (oxygen pulse), the two groups were not significantly different at any of the four workloads tested. The groups were compared further at workloads representing approximately 55, 65, 75, and 85 percent of VO2 max. HR was not significantly different at any of the four relative exercise intensities. VE was significantly greater in the obese at 85 percent of maximum only (P less than 0.05) and fb was significantly greater at 55, 75, and 85 percent of maximum. Whereas cardiorespiratory responses of moderately obese women are increased at absolute workloads when compared to that of leaner women, HR is similar at comparable intensities of exercise. VE is also similar at comparable intensities of exercise below ventilatory threshold but fb is greater. The effect of the higher fb on exercise tolerance is unknown.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
56.
In 1993, a case-control study by the Health and Safety Executive (HSE) assessed the risk of leukaemia and non-Hodgkin's lymphoma (LNHL) among children of fathers employed at the Sellafield nuclear installation in relation to paternal preconceptional irradiation (PPI). It concluded that the statistical association between risk of LNHL and PPI was confined to children born in the village of Seascale, where the dose-response was extremely high and very significant. In contrast, in 2002, a Cumbrian birth cohort study, investigating largely the same cases, concluded that this statistical association was not significantly different among children born inside and outside Seascale and estimated the dose-response inside Seascale to be much lower. This review makes a detailed comparison of the two studies, considering their design, data and analyses. The differences between their findings are due to: (i) differences in the distribution of offspring-years which are differential with respect to dose category and Seascale birth status, (ii) a non-Seascale high-dose case included in the Cumbrian but not the HSE study, (iii) differences between analyses using categorical and continuous PPI dose and (iv) the presence of Seascale controls with PPI over 200 mSv in the Cumbrian but not the HSE study. 相似文献
57.
A review of the literature on gender identity disorders is integrated with a case study presentation of a psychiatrically
disturbed nineteen-year-old transvestite youth. Accommodations and interventions made both with this patient and in the day
care program for psychiatrically disturbed youths that allowed him to live at home and be maintained despite severe pathology
are discussed.
Amaro Reyes, M.D. was formerly an attending Psychiatrist in the Community Division of Bronx Children's Psychiatric Center 相似文献
58.
Kay Teschke Susan M. Kennedy Andrew F. Olshan 《American journal of industrial medicine》1994,26(3):327-337
During an exposure monitoring study, 78 saw maintenance tradesmen were randomly assigned to be interviewed about their exposures using one of two questionnaire formats: open-ended and partly prompted questions about five categories of materials; and detailed prompting about 75 agents. The more open-ended questionnaire elicited fewer exposure responses overall, but more responses about agents not included on the detailed questionnaire. Composite materials and trade name products were more frequently cited as exposures than individual metals or compounds. Validity of responses was ascertained using air measurements (individual metals) or observations of the employees (composite materials). Sums of sensitivities and specificities were very low (near 1.0) for most of the metals for both types of questionnaire. For composite materials, validity improved substantially. Sensitivities with the partly prompted format (0.44–0.85) were always lower than with detailed prompting (0.80–1.00). Specificities were usually, but not always, higher with partial prompting (0.66–0.92) than with detailed prompting (0.18–0.86). Selection of questionnaire format for an epidemiologic study would depend on the likely prevalence of exposure in controls and the effects of trade-offs in sensitivity and specificity. 相似文献
59.
60.